Medical or surgical patients with coexisting mental disorders face significant barriers to accessing appropriate health care in general, and high quality cardiac services specifically. Evidence suggests that after acute myocardial infarction, patients with mental disorders tend to under-use invasive cardiac procedures including coronary artery bypass graft (CABG) surgery. In addition, our recent work shows that patients with mental disorders (such as psychiatric disorders or substance abuse disorders), when they do receive CABG surgery, are more likely to be treated by cardiac surgeons of inferior quality of care. The mental-disorder related disparities in quality of cardiac revascularization surgery are of particular concern for the Medicare population, as over 25% older persons are suffering mental disorders, and coronary heart disease (CHD) is one of the major causes of medical morbidity and mortality in this population. In addition, over 50% of all CABG surgeries are performed each year on individuals age 65 and over. However, relatively little is known about the dynamics underlying the disparity in quality of CABG surgery received by patients with coexisting mental disorders, a medically vulnerable group who has increasingly been shown to suffer from inappropriate medical and surgical care. The purpose of the study is to contribute to the understanding of the causes that lead to these observed disparities and the related clinical and policy implications, through an examination of physician behaviors in referring patients to CABG surgery. We will analyze Medicare claims data to examine actual physician practices, in which physician behavior in referring CHD patients with and without mental disorders will be compared. Multivariate statistical regression analyses will be employed. Findings of this study will help the design of future studies that aim to inform effective policy and practice initiatives to eliminate the disparities faced by elderly patients with mental disorders and better equip policy makers to address problems in the delivery of medical care to the vulnerable, mentally ill patients. PUBLIC HEALTH RELEVANCE: This proposed project was designed to examine the role of referring physicians in the mental-disorder related disparities in receipt of high-quality cardiac procedures among Medicare patients with coronary heart diseases.